In a heavy duty cargo handling vehicle, such as a reach stacker, a cab is generally installed on a frame so as to be slidable in a lateral direction or a longitudinal direction in order to ensure visibility. In this case, the cab is secured onto a slide base, and a pair of rails of nearly channel-shaped cross section are laid on the frame, with concave space portions of the rails being opposed to each other. A plurality of rollers annexed to opposite side surface portions of the slide base are provided so as to be rollable inside the concave space portions of these rails.